Chip Formation during Precision Cutting of Metallic Glass

Abstract

The chip formation mechanism during precision cutting of metallic glass (Zr55Cu30Ni5Al10 at%) was investigated around the glass transition temperature (673 K). Orthogonal cutting of metallic glass are conducted on a fly-cutting machine at various cutting speeds. The new surface of the chips was slightly shiny while the free surface exhibited lamellar slip structure. The cutting temperature was a proportional to the cutting ratio and chip shear angle. The surface integrity worsened with an increased flow of cutting chip due to an increase in the cutting speed. An increase in the cutting temperature caused the chips formation to change from flow type chips to discontinuous chips. When the cutting speed exceeded 300 m/min, the shear angle increased while the shear pitch of the chips decreased. It appears that when the cutting temperature exceeded the glass transition temperature, the strength of the metallic glass decreased and the ductility mode changed due to viscous flow.